Pros: A unique combination of a truly portable iPod speaker system with a docking station that doubles as a subwoofer, improving the portable unit’s bass response when they’re connected for tabletop audio and charging. Includes a replaceable rechargeable battery and a second battery bay for added runtime should you need it, as well as a wall adapter, Infrared remote control, and dock adapters. Attractive, simple design allows for uninterrupted transition between portable and desktop listening.

Cons: Docking the portable speaker with the subwoofer and charging dock was problematic in our review unit due to an issue currently being resolved by the manufacturer. While exceptionally convenient for users who would otherwise buy both portable and desktop audio solutions, standalone audio performance of portable piece isn’t as strong as leading less expensive portable competitors; similarly, combined performance doesn’t outstrip same- or lower-priced all-in-ones.

Originality has long since disappeared from the iPod speaker category: there are dozens of any given type of pocket, portable, or desktop design, each with relatively small distinctions that might appeal to certain users. So we are conceptually very enthusiastic about Gear4’s DUO (£150/$200), which the company accurately bills as a “Versatile Speaker System for iPod;” it is the first all-in-one unit we’ve seen that transforms from a slim portable speaker into a mid-sized desktop system. And save for a couple of non-trivial issues, DUO would have easily rated a high recommendation, as Gear4’s design makes a lot of sense and will appeal to many different types of iPod fans.

Only 9.1” wide and 5.2” tall, the black and silver DUO system begins with a metal and plastic speaker housing that’s merely 1.3” thick and entirely portable, containing two .75” tweeters, two 2-inch midrange drivers, and a rechargeable 9-hour battery. Volume and power buttons are located on its top, with an alternating red and blue light hidden behind the unified metal grille to provide standby or power on status. A metal kickstand flips out and locks into place on the unit’s back for stability, and a fold-out iPod dock is in front.

With two exceptions, this part of the DUO unit is extremely well designed. It has a power port on the back if you want to recharge it on its own, plus a line-in port for auxiliary audio, and not just one but two battery compartments; unlike most other rechargeable portable speakers we’ve seen, you can replace the included battery, and/or add a second pack if you need to double the system’s run time. Nine gold contacts are found on the back—more on them in a moment—and then there’s a physical power switch. Somewhat oddly located, this on/off switch is designed to let you know for sure that the portable half of the system is turned off when you’re traveling; the system’s top power button is apparently not enough in this regard. You needn’t use it at all when the front and back halves are connected to each other.

Nearly six inches deep, DUO’s subwoofer box is a combination charging station and bass enhancer for the portable speaker. It projects low-frequency sound from vents and a port on its back, contains rubberized feet for stability on a table, and features both line-in and power ports identical to the ones on the portable unit’s back. This piece is large and designed to be kept in one spot, then rejoined with the portable system whenever you want more full-bodied sound or battery power. Together, the two pieces look handsome, and while they’re over 8 inches deep with the iPod dock extended, the combined unit seems compact and clean by all-in-one iPod speaker standards.

When DUO is working perfectly, it does a very good job of delivering on the exact experience buyers would expect given the system’s price and physical characteristics. While the front half doesn’t put out much bass—an intentional omission on Gear4’s part—the tweeters and midrange drivers offer sound that’s otherwise close to $130-$150 portable competitors such as Logitech’s Pure-Fi Anywhere, JBL’s On Stage III or Altec Lansing’s iM600 in both detail and volume. Gear4’s choice of combined tweeters and midrange drivers strikes us as a wise one, even if the aforementioned companies are squeezing a wider frequency response out of their systems—they don’t have additional hardware to fall back on.

DUO does. When you dock its front half with its back, the subwoofer kicks in, delivering both more and cleaner bass than these portable systems. Make no mistake; when docked, the overall audio experience is better than what you’d get from a typical or even great inexpensive portable system. But by $200 iPod speaker standards, the overall audio experience is pleasant rather than staggering, notable more for how well the pieces work together than how powerful or loud its performance is. You can get a somewhat more lively portable or fully non-portable experience with DUO’s dedicated competitors on either side, but only this system has the versatility to function fully as either without forcing physical compromises.

Controlling DUO is straightforward. Gear4 includes a 13-button Infrared remote that features iPod menu navigation, track, volume, shuffle and repeat buttons, leaving out bass and treble controls. There are obvious reasons for this, particularly the complexities of trying to make the system’s front and back halves reliably sound nice together, but a bass level knob on DUO’s subwoofer would have been a welcome addition.

The only problem we experienced with DUO was that it didn’t always work perfectly. Something in either the nine internal gold contacts or a small trigger mechanism on the inner left hand side didn’t line up perfectly when we docked DUO’s front and back halves, so the subwoofer and charging features wouldn’t activate unless we wiggled the two parts together after docking. Once the quick wiggle was done, the subwoofer activated just as it was supposed to, and the iPod’s charging indicator lit up as well; as Gear4 promised, there’s no pause or other interruption in the audio, which just keeps on playing. The company is aware of the docking issue and remedying it in later production units, but a redesigned pin and lock system would really help.

While this docking issue wasn’t fatal to our rating of DUO, it did take away somewhat from what was otherwise a very positive experience. There’s no question that Gear4 has created a new iPod speaker category that offers users a novel combination of convenience and performance, offset only by the compromises it has reasonably made on portable sound quality and pricing. We’re confident that Gear4’s next iterations of DUO will build on this unit’s solid foundation, and we’re anxious to see what follow-up models will be capable of doing.

Editors' Note: iLounge only reviews products in "final" form, but many companies now change their offerings - sometimes several times - after our reviews have been published.
This iLounge article provides more information on this practice, known as revving.